The present invention relates to a system for supplying ink or writing fluid for writing instruments which operate with liquid ink or writing fluid.
With pens for writing fluid or liquid ink, it is customary to utilize the adhering ink or writing fluid level as the functional physical principle. Due to gas principles, this technical solution is extremely sensitive to fluctuations in temperature and air pressure. For modern types of hand-held writing instruments, such as felt-tip pens, ink ball-point pens, and similar instruments, there is provided a capillary retaining means of the ink or writing liquid by means of fibrous members, also known as plugs or wicks. This system is sufficiently insensitive to variations in temperature and air pressure, but provides a nonuniform writing fluid or liquid ink flow since the capillary cross-sectional areas differ. Not only does the average value fluctuate, but also the distribution of the capillary potentials fluctuates from one wick to another, and even the capillary potentials within a given wick show a wide spread. The latter also leads to only partial absorption of the writing fluid or liquid ink through the writing element. Furthermore, the material of the fiber member displaces a considerable amount of space, about 50 percent, which cannot be filled with writing fluid or liquid ink.
It is an object of the present invention to provide storage for writing fluid or liquid ink for hand-held writing instruments which, largely uninfluenced by climatic changes, allows a uniform supply of writing liquid or ink to the writing element and also allows one to write with a pen as long as possible on a single filling. The latter is to be achieved not only by means of a large holding capacity, but also with a high color intensity of the writing liquid or ink. The higher concentration of color as, for example, pen ink or writing liquid customarily also leads to a higher viscosity. Such higher viscosity inks or writing liquids cannot be used with writing instruments which operate pursuant to the aforementioned principle of the adhering level.